Gravity conveyor is an unpowered conveyor, which uses the force of gravity to move materials over a downward path. This conveyor is mostly used in vehicles such as trucks & rail receiving. In delivery vehicle, to upload a floor stacked delivery trailer, the unloading employees in the delivery trailer place the cartons on to the conveyor. With a push on the carton and gravity force, the carton flows to the end of the conveyor on to the dock area or for loading activity to the nose of the delivery truck. At this location, an employee removes the carton from the conveyor and stacks the carton onto the floor or onto a pallet board. The design of gravity conveyors is based on rules of thumb and actual operating experience.